The first global deep-sea trawl survey showed that in the past 60 years, actual fishing was 42% more than the United Nations Food and Agriculture Organization reported.

Lissette Victorero, chief expert of the National Oceanographic Center (NOC) in the United Kingdom, said that their research shows that the true catch is greatly underestimated and nearly 25 million tons of deep-sea fish are caught. These estimates need to be taken into account when making decisions regarding fisheries management. The study, published in Frontiers in Marine Science, shows that 42% of deep-sea fish are not registered, half are discarded, and half are undocumented.

University of Hawaii Lissette and colleagues used the data collected by the Sea Around Us project to study the history of 72 deep-sea fish. Various techniques are used to estimate the number of fish caught globally, including conversations with local experts and institutions.

Deep-sea fish often inhabit the seabed and ridges, and they may lose their lives when trawling in the deep sea. As the trawls are towed to the seabed, long-lived ecosystems are destroyed, including fragile cold-water corals and other fauna such as sponges, sea cucumbers and sea anemones.

Professor Les Watling from the University of Hawaii and the authors of the study explained that most of the fisheries they analyzed followed a typical “prosperity and depression” cycle that would collapse in less than a decade or two because of the general fecundity of deep-sea fish. Low, very slow growth, and highly susceptible to overfishing.

The study is part of a collaboration between the National Oceanographic Center, the University of Hawaii and the “Ocean Oceans Around Us” project, which is part of the ongoing research on future marine production capabilities at the National Oceanographic Center.